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| United States Patent |
6,131,559
|
|
Norris
, et al.
|
October 17, 2000
|
Convection oven with smoke management means
Abstract
A convection heating apparatus with smoke and grease management means and
an improved temperature controlled gas delivery system. The apparatus
includes an exterior cabinet, an interior chamber and intermediate walls
disposed between the exterior cabinet and interior chamber such that an
intermediate cavity is provided between the interior chamber and
intermediate walls and an outer cavity is provided between the exterior
cabinet and intermediate walls. The apparatus further includes a product
support, preferably a conveyor, disposed in the interior chamber. A blower
for circulating temperature controlled gas into said interior chamber is
also provided which is in fluid communication with at least one duct
(preferably a plurality) having a jet plate with orifices positioned to
direct temperature controlled gas toward the product support. A second
blower is provided for circulating air through the outer cavity and
intermediate cavity to cool the exterior cabinet walls and interior
chamber walls. An improved air delivery duct is provided having a dual
taper resulting in uniform distribution of the temperature controlled gas
to a food product. An air filtering system is also provided comprising a
perforated filter plate or louvers and/or catalytic converter disposed in
the temperature controlled gas return path.
| Inventors:
|
Norris; John R. (Plano, TX);
Dobie; Michael J. (Double Oak, TX);
Talley; Linda J. (Denton, TX);
High; Jarald E. (Grand Prairie, TX);
Dougherty; Carl J. (Grand Prairie, TX);
Cooper; Neal S. (North Richland Hills, TX)
|
| Assignee:
|
Patentsmith Technology, Ltd. (Dallas, TX)
|
| Appl. No.:
|
316719 |
| Filed:
|
May 21, 1999 |
| Current U.S. Class: |
126/21A; 55/440; 126/299R |
| Intern'l Class: |
A21B 001/00; F24C 015/20 |
| Field of Search: |
126/21 A,299 R
55/440,444,DIG. 36,DIG. 37,521
426/523
|
References Cited
U.S. Patent Documents
| 3780721 | Dec., 1973 | Druth | 126/21.
|
| 4108139 | Aug., 1978 | Gilliom et al. | 126/21.
|
| 4319898 | Mar., 1982 | Maierhofer | 55/444.
|
| 4516012 | May., 1985 | Smith et al. | 126/21.
|
| 4831238 | May., 1989 | Smith et al. | 126/21.
|
| 4928663 | May., 1990 | Nevin et al. | 126/21.
|
| 5131841 | Jul., 1992 | Smith et al. | 126/21.
|
| 5419239 | May., 1995 | Covington et al. | 126/21.
|
| 5499577 | Mar., 1996 | Tommasini | 126/21.
|
| 5598769 | Feb., 1997 | Luebke et al. | 99/395.
|
| 5655511 | Aug., 1997 | Prabhu et al. | 126/21.
|
| 5746118 | May., 1998 | Brunner et al. | 126/41.
|
| 5810898 | Sep., 1998 | Miller | 55/521.
|
| 5918589 | Jul., 1999 | Valle et al. | 126/21.
|
| 5927265 | Jul., 1999 | McKee et al. | 126/21.
|
| Foreign Patent Documents |
| 202331 | Nov., 1984 | JP | 126/21.
|
Primary Examiner: Lazarus; Ira S.
Assistant Examiner: Lee; David
Attorney, Agent or Firm: Sidley & Austin
Parent Case Text
CROSS REFERENCE TO RELATED APPLICATION
This application claims the benefit of prior filed provisional application
Serial No. 60/086,629, filed May 23, 1998.
Claims
What is claimed is:
1. An oven comprising:
exterior walls defining an exterior cabinet of said oven;
interior walls defining an interior chamber of said oven;
intermediate walls disposed between said exterior walls and said interior
walls, said intermediate walls and said interior walls defining an
intermediate cavity between said interior and intermediate walls and said
interior walls and said exterior walls defining an outer cavity between
said exterior and intermediate walls;
a product support disposed in said interior chamber;
a first blower for circulating temperature controlled gas into said
interior chamber, said first blower being in fluid communication with at
least one duct, said duct having a jet plate with a plurality of orifices
positioned to direct said temperature controlled gas toward said product
support within the interior chamber of said oven; and
at least one other blower in fluid communication with said outer cavity and
with said intermediate cavity capable of circulating air through said
outer cavity and circulating air through said intermediate cavity for
controlling the temperature of said interior walls and said exterior
walls.
2. The oven of claim 1 wherein said at least one other blower circulates
ambient air.
3. The oven of claim 1 wherein there are separate blowers to circulate air
through said outer cavity and through said intermediate cavity.
4. The oven of claim 1 wherein said at least one other blower comprises a
single blower, said oven further including a diverter associated with said
outer cavity and said intermediate cavity, said diverter being adjustable
to control the amount of said air circulated through said outer cavity and
through said intermediate cavity.
5. The oven of claim 4 wherein said diverter is adjustable to substantially
eliminate said air circulation through said intermediate cavity.
6. The oven of claim 1 further including an exhaust conduit for exhausting
at least a portion of said temperature controlled gas from the oven.
7. The oven of claim 6 further including a conduit whereby a portion of
said air circulated through said outer cavity and/or through said
intermediate cavity is mixed with said exhausted portion of temperature
controlled gas.
8. The oven of claim 6 further comprising a catalytic converter positioned
to treat said exhausted portion of temperature controlled gas.
9. The oven of claim 6 further comprising a cyclonic separator positioned
downstream of said exhaust conduit.
10. The oven of claim 1 where said interior walls include an inclined
floor, said inclined floor being sloped toward a drain pipe leading out of
said oven.
11. The oven of claim 1 further comprising a conduit for providing water
into said interior chamber of said oven.
12. The oven of claim 1 wherein said product support comprises a conveyor.
13. The oven of claim 1 where said at least one duct comprises a plurality
of ducts.
14. The oven of claim 13 wherein there is at least one duct above said
product support and at least one duct below said product support.
15. The oven of claim 14 wherein there is a plurality of ducts above and a
plurality of ducts below said product support.
16. A method of heating a food product with the oven of claim 1 comprising:
providing a food product on said product support;
circulating heated gas having a temperature into said interior chamber
through said at least one duct; and
controlling the temperature of the interior walls of said oven by
circulating air through said intermediate cavity.
17. The method of claim 16 further comprising the step of circulating air
through said outer cavity to control the temperature of said exterior
walls of said oven.
18. The method of claim 16 wherein air is circulated through said
intermediate cavity to produce an interior wall temperature that will not
produce smoke upon contact with food particles.
19. The method of claim 16 wherein air circulated through said intermediate
cavity is reduced to produce an interior wall temperature that will
produce smoke upon contact with food particles.
20. A method of cleaning the oven of claim 1 comprising:
circulating air through said outer cavity of said oven;
restricting air circulation through said intermediate cavity of said oven
to allow said interior walls to reach elevated temperatures;
bringing the temperature of the interior chamber of said oven to at least
300.degree. F.;
increasing the temperature of the interior chamber of the oven to at least
about 600.degree. F. allowing smoke to be produced and maintaining this
temperature until smoke production is substantially ceased;
increasing the temperature of the interior chamber of said oven by about
100.degree. F. allowing smoke to be produced and maintaining this
temperature until smoke production is substantially ceased; and
increasing the temperature of the interior chamber of said oven by about
200.degree. F. and maintaining this temperature until smoke production is
substantially ceased.
21. A method of cleaning the oven of claim 1 comprising:
circulating air through said outer cavity of said oven;
restricting air circulation through said intermediate cavity of said oven
to allow said interior walls to reach elevated temperatures; and
providing a temperature in the interior chamber of said oven sufficient to
pyrolitically clean said interior chamber.
22. A method of cleaning the oven of claim 12 comprising:
circulating air through said outer cavity of said oven;
restricting air circulation through said intermediate cavity of said oven
to allow said interior walls to reach elevated temperatures;
providing an elevated temperature in the interior chamber of said oven
sufficient to pyrolitically clean said interior chamber; and
moving said conveyor through said interior chamber while said chamber is at
said elevated temperature.
23. The oven of claim 1 wherein said at least one duct has a proximal end
and a distal end and a length extending between said proximal end to said
distal end; and said duct has an inlet opening adjacent said proximal end
through which said gas enters; said duct comprising a jet plate having a
plurality of orifices along said length through which gas may exit said
duct, said duct further comprising a first tapered portion adjacent said
proximal end and a second tapered portion adjacent said distal end, said
first tapered portion having a greater angle of taper than said second
tapered portion.
24. The oven of claim 23 wherein said at least one duct comprises a
plurality of ducts.
25. The oven of claim 24 wherein said plurality of ducts comprises at least
one duct above and at least one duct below said product support.
26. The oven of claim 24 wherein said plurality of ducts comprises a
plurality of ducts above said product support and a plurality of ducts
below said product support.
27. The oven of claim 1 further comprising:
at least one filter plate disposed within said interior chamber separating
said interior chamber into a cooking chamber and an air return chamber,
said plate having perforations formed therein and having a plurality of
bends.
28. The oven of claim 27 wherein said plurality of bends comprises
accordion folds.
29. The oven of claim 27 wherein said at least one filter plate comprises a
plurality of filter plates each having perforations and an accordion fold
shape, said filter plates being disposed in a nested configuration.
30. The oven of claim 28 wherein said filter plate has a first side and a
second side, said perforations in said filter plate comprising rows of
punch-out sections extending from said first side and from said second
side.
31. The oven of claim 1 wherein said interior chamber comprises a cooking
chamber and an air return chamber, said oven having a return path for said
temperature controlled gas whereby at least a portion of said gas is
returned to said blower after entering said cooking chamber and said oven
having at least one catalytic converter disposed in said gas return path.
32. The oven of claim 31 wherein said at least one catalytic converter
comprises a plurality of catalytic converters.
33. The invention of claim 31 further comprising at least one perforated
filter plate disposed within said interior chamber separating said
interior chamber into said cooking chamber and said air return chamber.
34. The invention of claim 33 wherein said at least one perforated filter
plate has an accordian fold shape.
35. The invention of claim 1 further comprising a plurality of louvers
disposed in said interior chamber separating said interior chamber into a
cooking chamber and an air return chamber, said louvers being downwardly
inclined toward said cooking chamber, said louvers being positioned such
that said temperature controlled gas passes through said louvers before
returning to said blower for recirculation into said at least one duct.
36. The invention of claim 31 further comprising a plurality of louvers
disposed in said interior chamber separating said interior chamber into a
cooking chamber and an air return chamber, said louvers being downwardly
inclined toward said cooking chamber, said louvers being positioned such
that said temperature controlled gas passes through said louvers before
returning to said blower for recirculation into said at least one duct.
Description
FIELD OF INVENTION
The present invention relates to high heat transfer rate convection ovens
utilizing heated jets of air to cook food product and incorporating grease
and smoke management features to prevent undesired off-flavor in the food
product.
BACKGROUND OF THE INVENTION
The present invention relates to a high velocity convection oven capable of
cooking foods that are traditionally cooked by deep fat frying methods,
without producing undesired smoke and smoke flavor in the food. More
specifically, the oven of the present invention produces high velocity
jets of air to cook food product while the food product is moved relative
to the air jets, with the preferred method of moving food product being a
conveyor assembly. High velocity convection ovens of this type are
generally referred to as impingement ovens.
In sum, the oven is characterized by its production of very high transfer
rates needed for cooking traditionally deep fat fried foods with air.
While conventional impingement type ovens (e.g., see U.S. Pat. No.
4,338,911) have been known to produce heat transfer rates in the range of
12-15 (as measured by a heat transfer rate measurement device of the type
described in U.S. Pat. No. 5,161,889), the oven of the present invention
is capable of producing heat transfer rates of up to 25 and greater. At
the same time, the present oven design also has features which control the
amount of smoke produced in the cooking cavity, thereby reducing or
eliminating the off-flavor that could be caused by the smoke.
Further, the oven includes dual cavities surrounding the cooking chamber
through which room temperature air is circulated. This "cool skin" feature
cools the interior walls of the cooking chamber to promote grease
collection and retard smoke production. This feature also cools the
exterior walls of the oven making the oven safer for use. In addition, the
oven of the present invention features an improved air delivery (duct)
design that produces more even distribution of temperature controlled
cooking gasses to the food product and self-cleaning capabilities using
pyrolytic cleaning methods.
SUMMARY OF THE INVENTION
The present invention relates to a convection heating apparatus with smoke
and grease management means and an improved temperature controlled gas
delivery system. The apparatus includes an exterior cabinet, an interior
chamber and intermediate walls disposed between the exterior cabinet and
interior chamber such that an intermediate cavity is provided between the
interior chamber and intermediate walls and an outer cavity is provided
between the exterior cabinet and intermediate walls. The apparatus further
includes a product support, preferably a conveyor, disposed in the
interior chamber. A blower for circulating temperature controlled gas into
said interior chamber is also provided which is in fluid communication
with at least one duct (preferably a plurality) having a jet plate with
orifices positioned to direct temperature controlled gas toward the
product support. The apparatus further includes second blower capable of
circulating air through the outer cavity and intermediate cavity thereby
cooling the exterior cabinet walls and interior chamber walls. In one
embodiment of the invention, separate blowers are used to circulate air
through the outer cavity and through the intermediate cavity of the
apparatus.
In a preferred embodiment of the invention, a single blower is used to
circulate air through the outer and intermediate cavities and a diverter
vane is used to control the amount of air circulated through the outer and
intermediate cavities.
In another embodiment of the invention the oven further includes an exhaust
conduit for exhausting at least a portion of the temperature controlled
gas (i.e., the cooking gas) from the oven. In a preferred construction,
the apparatus further includes a conduit means whereby a portion of the
air circulated through the outer cavity and/or through the intermediate
cavity is mixed with the exhausted portion of temperature controlled gas
thereby reducing the temperature of the exhaust stream.
In another preferred embodiment of the invention, the apparatus may include
a catalytic converter positioned to treat the exhausted portion of
temperature controlled gas.
In alternative preferred embodiments of the invention, the apparatus may
also include a cyclonic separator positioned downstream of the exhaust
conduit, an interior chamber with an inclined floor and drain pipe leading
out of said oven and a water conduit for cleaning purposes.
The invention further includes methods of heating a food product with the
apparatus described herein and cleaning said oven. Generally, the method
of cooking includes: providing a food product the product support;
circulating heated gas into the interior chamber; and controlling the
temperature of the interior walls the oven by circulating air through the
intermediate cavity. In a preferred method of cooking, air is also
circulated through the outer cavity of the apparatus to control the
temperature of the exterior walls.
In the method of cleaning the oven air is circulated through the outer
cavity of the oven, the interior chamber temperature is elevated and air
flow through the intermediate cavity is restricted to allow the interior
chamber walls to reach an elevated pyrolytic cleaning temperature. In a
preferred embodiment, the temperature is elevated in steps.
In another aspect of the invention, an improved air delivery duct is
provided having a proximal end and a distal end and a length extending
between said proximal end to said distal end. The duct has an inlet
opening adjacent said proximal end through which temperature controlled
gas (cooking gas) and has a plurality of orifices along its length through
which the gas may exit. The duct has a first tapered portion adjacent the
proximal end and a second tapered portion adjacent the distal end, with
first tapered portion having a greater angle of taper than the second
tapered portion.
I another aspect of the invention the oven includes a perforated filter
plate disposed within the interior chamber or, alternatively a plurality
of inclined louvers, separating the interior chamber into a cooking
chamber and an air return chamber. To increase the capture of entrained
food particles the plate has a plurality of bends, preferably an accordion
fold configuration.
In yet another aspect of the invention, the oven includes at least one
catalytic converter disposed in the temperature controlled gas return path
.
BRIEF DESCRIPTION OF DRAWINGS
For a more complete understanding of the present invention, and for further
advantages thereof, reference is now made to the following description,
taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a perspective view of the oven of the present invention partially
depicting components thereof;
FIG. 2 is a perspective view of the oven of the present invention partially
depicting components thereof;
FIG. 3 is a perspective view of the oven of the present invention partially
depicting components thereof;
FIG. 4 is a perspective view of the oven of the present invention partially
depicting components thereof;
FIG. 5 is a perspective view of the oven of the present invention partially
depicting components thereof;
FIG. 6 is a perspective view of the oven of the present invention partially
depicting components thereof;
FIG. 7 is a cross section view of the oven of the present invention
partially depicting components thereof;
FIG. 8 is a perspective view of the blower assembly and exhaust assembly of
the present invention partially depicting components thereof;
FIG. 9 is a perspective view of the oven of the present invention partially
depicting components thereof;
FIG. 10 is a cross section view of the oven of the present invention
partially depicting components thereof;
FIG. 11 is a perspective view of the oven of the present invention
(electric version) partially depicting components thereof;
FIG. 12 is a perspective view of the oven of the present invention
(electric version) partially depicting components thereof;
FIG. 13 is a cross section view of the oven of the present invention
partially depicting components thereof;
FIG. 14 is a perspective view of the oven of the present invention
partially depicting the components of the conveyor assembly thereof,
FIG. 15 is a perspective view of the oven of the present invention
depicting components of the blower assembly thereof;
FIG. 16 shows multiple views of the heat slinger component of the present
invention;
FIG. 17 is a perspective view of the diverter assembly of the present
invention;
FIG. 18 shows multiple views of the catalytic converter holder of the
present invention;
FIG. 19 shows multiple views of a jet plate of the present invention;
FIG. 20 shows multiple views of a jet plate of the present invention;
FIG. 21 is a perspective view of the blower housing, plenum assembly and
air delivery ducts of the present invention;
FIG. 22 shows multiple views of blower housing and plenum assembly of the
present invention;
FIG. 23 is a top view of the blower housing, plenum assembly and air
delivery ducts of the present invention;
FIG. 24 shows multiple views of a preferred duct design for the oven of the
present invention;
FIG. 25 is a side view of a preferred duct design for the oven of the
present invention;
FIG. 26 shows multiple views of a filter assembly of the present invention;
FIG. 27 shows multiple views of a filter assembly of the present invention;
FIG. 28 shows multiple views of the water reservoir assembly of the present
invention;
FIG. 29 shows multiple views of the eyelid assembly of the present
invention;
FIG. 30 is a view of oven of the present invention depicting air flow
through said oven;
FIG. 31 is a side view of the oven of the present invention partially
depicting components thereof;
FIG. 32 is a schematic (side view) representation of the air flow through
the oven of the present invention;
FIG. 33 is a schematic (side view) representation of the air flow through
the oven of the present invention depicting a cyclonic separator;
FIG. 34 is a graphic representation of electronic controls for the oven of
the present invention; and
FIG. 35 is a cross section (side view) of an embodiment of the present
invention partially depicting components thereof.
A detailed description of the oven is provided below.
DETAILED DESCRIPTION OF THE INVENTION
Drawings of preferred embodiments of the invention are annexed hereto so
that the invention may be better and more fully understood. FIGS. 1-10
depict a larger, gas heated version of an oven embodying the present
invention. FIGS. 11-23 depict a smaller, electrically heated version of an
oven embodying the present invention. FIGS. 24-34 depict general
representations of both gas and electrically heated ovens and components
thereof. Because most of the structures and parts of these two embodiments
differ only in regard to size and numbers the same numeral references will
be used for both embodiments to designate like parts and structures
throughout the figures of the drawings. Any significant differences
between the gas heated and electrically heated embodiments shall be
expressly discussed herein.
Referring to FIGS. 1-13 and 30-33, there is shown the oven 10 of the
present invention. Oven 10 includes an exterior cabinet 12 defined by
exterior side walls 16 and 18, exterior front wall 20, exterior rear wall
22, exterior top wall 24, and exterior bottom wall 26, all spaced from
each other (hereinafter collectively referred to as the "exterior walls
29" of the cabinet or oven). The configuration of cabinet 12 may vary
depending upon the type of oven installation. Generally, cabinet 12 will
comprise rectangularly-shaped exterior walls and be of a box shape.
Particularly suitable materials for the exterior walls include aluminized
steel and stainless steel. Eyelids 27 (FIGS. 29 and 31), composed of sheet
stainless steel, are adjustably mounted to the exterior side walls
adjacent the exit and entrance openings in the oven by screw means or
other suitable means. The adjustable eyelids or covers can be moved to
substantially cover the entrance and exit openings when desired, such as
during the pyrolytic cleaning operation of the oven.
Oven 10 further includes an interior chamber 28 defined by interior side
walls 30 and 32, interior front wall 34, interior rear wall 36, interior
top wall 38, and interior bottom wall 40 spaced from each other
(hereinafter collectively referred to as the "interior walls 41" of the
interior chamber or oven). As shown in FIG. 30, the interior chamber 28 is
divided into a cooking chamber 28a and air return chamber 28b. Bottom wall
40 is sloped downwardly toward drain opening 42 which has connected
thereto drain pipe 43 extending through the intermediate and exterior
bottom walls 56 and 26, respectively. Preferably, the slope angle for
bottom wall 40 is between about 2-10 degrees, with an angle of about 2-4
degrees being preferred. Particularly suitable materials for the interior
walls of the interior chamber include aluminized steel and stainless
steel.
Disposed between the exterior and interior walls of the oven is
intermediate shell 44 defined by intermediate side walls 46 and 48,
intermediate front wall 50, intermediate rear wall 52, intermediate top
wall 54, and intermediate bottom wall 56 spaced from each other
(hereinafter collectively referred to as the "intermediate walls 57" of
the oven). Particularly suitable materials for the intermediate walls
include aluminized steel and stainless steel.
It has also been found that the intermediate walls can be constructed of an
insulating board material 45 such as Marinite board. Alternatively, an
insulating board, such as Marinite board, may be mounted in an abutting
relationship with the intermediate walls (FIG. 35). This alternative
design has been found to improve the performance of the oven in that the
exterior wall temperature is reduced while allowing higher temperatures to
be maintained in the cooking chamber, thus allowing smaller blowers to be
used for circulation of air through the outer and intermediate cavities.
As shown best in FIGS. 7, 13 and 30, the space between the exterior walls
and intermediate walls defines an outer cavity 60. The space between the
intermediate walls and interior walls defines an intermediate cavity 62.
In the embodiments shown there is no fluid communication between the
intermediate cavity, outer cavity and the cooking chamber.
As shown in FIGS. 1-2, 14, and 31, food products are transported into and
through cooking chamber 28a by conveyor assembly 70 of conventional design
(e.g., see U.S. Pat. No. 4,338,911 and U.S. Pat. No. 4,462,383, hereby
incorporated by reference). As shown, conveyor assembly 70 preferably
comprises a continuous loop wire mesh conveyor belt 72 which extends
through entrance opening 74 and exit opening 76 in the oven and is
horizontally disposed as it travels through cooking chamber 28a. A
conventional flat-flex stainless steel wire mesh belt is suitable. The
width of the belt is a matter of choice, but a belt width of about 12-16
inches is very suitable for the larger gas heated oven and a belt width of
about 9-12 inches is very suitable for the smaller electrically heated
oven. Conveyor belt 72 is supported by rails 78 and can be driven by a
conventional variable speed electric motor. Rails 78 can be mounted in the
oven by welding them to lower ducts 102 or using other conventional means
to secure the rails in the oven. Preferably, the conveyor assembly extends
a sufficient distance from the exit and entrance openings in the oven to
allow food products to be readily positioned on the conveyor belt for
travel through the cooking chamber of the oven and removal upon exiting
the oven.
With respect to the conveyance of food product through the oven, it is
desirable to incorporate a programmable conveyor speed controller to
control cook time. Such controllers are well known in the field of
conveyorized impingement ovens. Such controllers can be calibrated to
indicate the time the food product is to remain in the oven depending upon
the requirement for a particular food product.
Disposed within cooking chamber 28a and in fluid communication with plenum
320 are upper air dispensing ducts (or fingers) 100 disposed above
conveyor belt 72 and lower air dispensing ducts (or fingers) 102 disposed
below conveyor belt 72. These ducts can be constructed of any of several
known materials capable of withstanding and performing under the high
temperature conditions of the oven, such as aluminized steels and
stainless steels. Ducts 100 and 102 are hollow and arranged to direct jets
of heated air against the surface of food product on the conveyor belt. As
shown, the ducts are preferably tapered along their respective
longitudinal axes, with the cross sectional area (perpendicular to
longitudinal axes) of the ducts being greater at their respective proximal
ends 104 (i.e., the ends adjacent plenum 320) and smaller at their distal
ends 106. Ducts 100 and 102 are welded or otherwise secured to wall 310
with inlet openings 108 of the ducts adjacent to and in fluid
communication with outlet opening 322 in plenum 320. Each of the hollow
tapered fingers 100 and 102 have a perforated surface or jet plate 110
facing the conveyor belt in which orifices or openings 112 are formed.
Openings 112 are designed to direct streams of heated air against a food
product being transported on the conveyor belt.
The number, size and arrangement of the ducts 100 and 102 can vary
depending on the size of the oven and the desired results. FIG. 8 depicts
a preferred air duct arrangement for a larger, gas heated oven having a
conveyor width of about 14 inches, a length of about 36-38 inches (side
wall to side wall), a height of about 22 inches and a width of about 32
inches. As shown, the gas heated oven includes six ducts above the
conveyor assembly and six ducts below the conveyor assembly. In contrast,
the smaller electric oven is approximately 22-24 inches long, about 15
inches in height, about 28 inches wide and has three fingers above and
three fingers below the conveyor belt (FIG. 21).
The distance from the upper jet plate to the conveyor belt is approximately
1 inch. Likewise, the distance between the lower jet plates and conveyor
belt is 1 inch. Further, note that fingers 100 and 102 are disposed above
and below the conveyor assembly in non-opposing positions. That is, the
upper and lower fingers are staggered. Also, note the absence of fingers
extending continuously to the exit opening of the oven adjacent the blower
assembly. It has been found that the blower creates a suction effect in
this region make the placement of fingers in this region ineffective.
In a preferred embodiment, the openings 112 in jet plates 110 comprise
circular nozzles as shown in FIGS. 19 and 20, with the centers of the
openings being spaced apart a distance not exceeding four times the
diameter of the openings. Specifically, upper air duct 100 has a plurality
of nozzles 112 directed downwardly toward the conveyor belt 72. Lower air
ducts 102 have a plurality of nozzles 112 directed upwardly toward the
conveyor belt. FIG. 19 shows a preferred arrangement of the nozzles 112
wherein the nozzles are arranged in three rows from distal end to proximal
end with the rows being offset from each other. The nozzle openings have
approximate diameters of 0.44 inches and extend about 1/8" from the jet
plate surface in the direction of the conveyor. In this preferred
embodiment, the rows of nozzles are offset by about 0.383 inches from the
adjacent row and the rows are spaced about one inch apart, taken from
lines drawn through each row at the center of the nozzles. As stated, the
size, number, and arrangement of the nozzles may vary. The illustrated jet
plate and nozzle arrangement is a preferred arrangement for an oven having
fingers with 10" jet plates. Another arrangement is shown in FIG. 20.
In another preferred embodiment of the invention, upper and lower ducts
100a and 102a closest to the exit and entrance openings 76, 74 are shaped
to angle inwardly from the exit and entrance openings (FIG. 8). The angle
of the jet plate surface in ducts 100a and 102a is such that the escape of
heated air from the entrance and exit openings is minimized. Preferably,
the perforated surface of the angled ducts is inclined toward the interior
of the chamber at an angle in the range of 3.degree. to 30.degree.
relative to the vertical plane of the exit and entrance openings. With the
air streams inclined toward the interior of the oven, most of the hot air
returned to the interior of the oven.
In a most preferred embodiment of the present invention, the ducts 100 and
102 have a dual taper configuration. As shown in FIGS. 24 and 25, the dual
tapered duct 120 has a first tapered portion 122 adjacent the proximal end
104 of the duct and a second tapered portion 124 adjacent the distal end
106 of the duct. As shown, the first tapered portion 122 has a greater
angle of taper than the second tapered portion 124 which has a gentler
slope. The first tapered portion 122 extends approximately one-quarter to
one-half of the length of the duct. The degree of taper in the first and
second tapered portions may vary. Preferably, the first tapered portion
122 tapers down 1 inch for every 1.5 to 3 inches of length and the second
tapered portion 124 tapers 1 inch for every 7 to 16 inches of length. This
dual taper duct configuration has been found to provide improved evenness
of air flow from the openings along the length of the ducts and thus
improves evenness of cooking.
Referring to FIGS. 3, 26-27, and 30 disposed above upper ducts 100 and
below lower ducts 102 are filter assemblies 130 and 132, respectively.
Filter assemblies 130, 132 separate the cooking chamber 28a from the
return air chamber 28b of the oven and comprise a plurality of
accordion-folded, perforated plates 134 and 136 secured within frames 138,
140 which are mounted to top and bottom interior walls 38, 40,
respectively, by suitable means such as welding. Folded plates 134 and 136
can be constructed of any material capable of withstanding the high
temperatures associated with the oven. The preferred material is carbon
steel. Stainless steel is another suitable material. As shown in greater
detail in FIG. 27, the perforations 142 in the plates are formed by rows
of punch-out sections 143 extending from a first side 144 and second side
146 in alternating fashion.
The arrangement of the folded plates with respect to each other may vary.
In FIGS. 3 and 27, the plates are spaced from each other a small distance
and are in a nested relationship. FIGS. 26 and 30 show the use of two
perforated plates in a non-nested configuration, i.e. with peaks 148 of
one plate meeting the valleys 150 in the other plate. By providing
perforated plates with an accordion fold, air returning from the fingers
passes over a greater surface area then would be encountered with a flat
plate. This filter assembly design also provides the benefit of slowing
the air flow toward the plenum at normal operating conditions from about
2000 ft/min to 300-500 ft/min. At this lower speed, air-entrained
particles of grease (and other materials) from the food product cannot
maneuver the tortuous path created by the filter design and thus the
filter assembly acts as a barrier between the cooking chamber and the
return air chamber behind the filter assembly. While the plates in the
preferred embodiment of this invention are accordion folded, the plates
may be shaped in other (not flat) ways increase the surface area over
which return air travels, such as providing repeating 90.degree. bends in
the plates or a sine curve pattern.
Mounted within the interior of the oven behind the accordion filters are
catalytic converter boxes 160 (FIGS. 1-3, 6, 9, and 10). Catalytic
converter boxes 160 hold catalytically coated materials 162, i.e.,
catalytic converters. Preferably, the catalytic material is a
catalytically coated ceramic material. A most preferred catalytic
converter material is a palladium-based ceramic catalytic converter
available from Applied Ceramics. As the heated air passes the catalytic
converter materials 162, smoke and vapor (i.e., volatile organic
compounds) in the circulating airstream are more completely oxidized to
CO.sup.2 and H.sup.2 O to prevent smoke from being recirculated into the
cooking chamber.
In an alternative arrangement (FIG. 35), the filter assembly 130 may
comprise a louver configuration, rather than a folded plate configuration.
The louvers 180 can be made of any suitable materials such as stainless
steel. The louvers shown are constructed of elongated, hollow stainless
steel members and are welded in place. As shown in FIG. 35, the louvers
are disposed in the air return path (represented by arrows) and separate
the interior chamber 28 into a cooking chamber 28a and air return chamber
28b. After the temperature controlled gas hits a food product the gas
returns through the louvers 180, contacting the louvers and allowing
entrained particles or grease to be collected on the louvers. As shown,
the louvers incline downwardly toward the cooking chamber side 28a of the
oven, preventing collected grease and particles from running into the air
return chamber 28b. Also, as shown, the air return path is on the top
only. In this arrangement, gravity forces assist the system in keeping
grease and other entrained food particles from the air return chamber of
the oven.
As shown in the figures, most particularly FIGS. 8-9, 15-16, and 22-23, a
blower/plenum assembly 300 is mounted within the air return portion 28b of
interior chamber 28. Blower/plenum assembly 300 includes a housing 302
comprising top wall 304, bottom wall 306 and having a curved end wall
portion 308 shaped for housing a blower wheel 330. Extending from the
curved end wall 308 adjacent ducts 100, 102 is front wall 310 disposed
substantially perpendicular to the longitudinal axes of the ducts.
Extending from the opposite end of the curved wall 308 (adjacent the rear
portion of the oven) is rear wall 312 which tapers toward and is secured
to front wall 310 adjacent the entrance opening of the oven. Top wall 304
and bottom wall 306 are secured to front wall 310, rear wall 312 and
curved end wall 308 by welding or other suitable means such as pop
riveting. A plenum 320 is formed by front wall 310, rear wall 312, top
wall 304 and bottom wall 306. Outlet openings 322 are formed in front wall
310. Optionally, plenum 320 may also include a diverter or splitter 324
(FIG. 30) for more efficient direction of air toward the outlet openings
of the plenum and into the ducts 100 and 102. The walls of the housing and
plenum are preferably made of stainless steel.
Blower wheel 330 is mounted on driven shaft 332 within housing 302 adjacent
the curved end wall 308. Blower wheel 330 draws heated air from the return
air chamber 28b and circulates the air into plenum 320. As best
illustrated in FIGS. 15 and 16, a variable speed, split face motor 336 has
a driven shaft 338 which is connected to driven shaft 332 by suitable
means such as a belt 340 and pulleys 342 and 344. The end portions of
driven shaft 332 extend from blower/plenum housing 302 and through
frustroconical shrouds 346 and 348 where said ends are rotatably mounted
to interior top wall 38 and interior bottom wall 40, respectively.
Frustroconical shroud 348 is mounted to the bottom wall by welding or
other suitable means and houses bearing 350 and heat slinger 352 which are
operably connected to the end of shaft 332. Frustroconical shroud 346 is
mounted to the top wall by welding or other suitable means and houses
bearing 354 and heat slinger 356 which are operably connected to the
opposite end of shaft 332. Heat slingers 352 and 356 (FIG. 6) serve to
reduce the temperature adjacent the upper and lower portions of the shaft,
thereby minimizing bearing failure. The shroud may also house insulating
materials, such as mineral wool insulation, to further protect the
underlying bearings from the adverse effects of heat.
Preferably, to generate high heat transfer rates desirable for cooking
foods that are traditionally deep fat fried, the blower wheel and blower
motor should be capable of producing air velocities of about 5000-6000
ft/min from ducts 100 and 102. For larger gas-heated ovens, it has been
found that a 1.5 horsepower motor is suitable. Further, because the wheel
will be subjected to high temperatures, it is preferred that the wheel
have sufficiently high heat resistance, preferably 900.degree. F. or
greater. A particularly suitable blower wheel is a Revcor forward-inclined
industrial wheel having a 91/8" diameter and three inch width (912-300
Model). This recommended motor and blower wheel configuration is capable
of producing the high velocity from the ducts referred to above and
produces very high heat transfer rates of about 20 to 27 BTU/(hr.)(sq.
ft.)(.degree. F.), as measured by a heat transfer measurement device of
the type disclosed U.S. Pat. No. 5,161,889. Further, with larger
gas-heated ovens, two double inlet blower wheels may be used. When using
two wheels, left and right blower wheels can be bolted back-to-back on one
hub.
For smaller electric-heated ovens, a smaller split face motor is suitable
for driving the blower. For example, a three-fourths horsepower split-face
motor having a 1/3 horsepower idle mode is suitable. The 1/3 horsepower
phase produces lower noise and provides sufficient airflow in the cleaning
mode of the oven.
Referring to FIGS. 30 and 17, the wall cooling features (i.e., "cool skin")
of the present oven shall now be described. As shown in FIG. 30, there is
provided a cooling blower assembly 400 operably secured to oven cabinet
12. Blower assembly 400 includes blower 402 and conduit 404 mounted to the
blower. Conduit 404 is secured to cabinet 12 and is fluid communication
with outer cavity 60 through outer cavity opening 61 and with intermediate
cavity 62 through intermediate cavity opening 406. Rotatably mounted
within conduit 404 is diverter vane 408. Diverter vane 408 is controlled
by diverter rod 410 which is secured thereto. By moving the diverter vane
408 with the diverter rod 410, air from blower 402 can be directed to the
outer cavity 60 (Position C), intermediate cavity 62 (Position A) or both
cavities (Position B), as shown in FIG. 30. Blower 402 can be of any type
capable of producing sufficient pressure (1/2 inch of water) for this
circulation pattern. A forward inclined metal blower with the
aforementioned pressure capabilities has been found to be suitable. The
arrangement described above and shown in FIG. 30 has been found to be
particularly effective because the blower is displaced from the oven
cabinet and is always running whether a cooking or cleaning operation is
being performed. Thus the blower is maintained at a sufficiently low
temperature. In contrast, in a less preferred embodiment shown in FIGS.
1-10, separate axial fans 420 and 422 are mounted to the oven walls and
circulate air through the exterior and intermediate cavities of the oven.
However, when the fans serving the intermediate cavity of the oven are
turned off during pyrolytic cleaning operations (described infra), the
fans are subjected to elevated temperatures and may be damaged. Thus,
axial fans 420, 422 and vent 424 are shown only as a less preferred
embodiment of the invention and the depiction of these structures should
be disregarded in the drawings when implementing the preferred embodiment
described above and shown in FIGS. 17 and 30.
Referring to FIG. 30, during normal cooking operation, diverter 408 is in
Position B and air is circulated through outer cavity 60 and intermediate
cavity 62, thereby cooling both the exterior and interior walls of the
oven. The cooling of the interior cooking chamber walls enhances the
ability to collect grease and prevent undesired smoke during cooking
operations. Grease tends to accumulate and gather on cooler surfaces. With
air circulating through the intermediate cavity the interior walls of the
oven in the cooking chamber are maintained at about 300.degree. F. while
the air temperature in the cooking chamber (and other structure within the
cooking chamber) is maintained at the selected cooking temperature which
generally ranges from about 350-500.degree. F., most typically about
425.degree. F. This lower cooking chamber wall temperature is also below
the smoke point of most oils found in food products. Consequently, the
oils and grease collecting on the cooler walls do not produce substantial
amounts of smoke. Of course, if a smoke flavor in the food is desired, the
diverter can be adjusted so that more air is circulated through the
exterior cavity and less through the interior cavity, thereby reducing the
cooling effect of the air in the intermediate cavity and raising the
temperature of the cooking chamber walls. Smoke will be produced when the
interior walls reach the smoke point temperature of the oils produced by
the food.
As previously stated, the oven of the present invention can be heated by
conventional heating means, such as a flame heated heat exchanger (gas) or
an electrical resistance heating element. The oven illustrated in FIGS.
11-21 depicts an electrically heated oven. In this embodiment of the
invention, electrical heating elements 428 are disposed in the return air
chamber 28b of the oven, thereby heating the air which is drawn into the
plenum 320 by the blower wheel 330. Particularly suitable electric heating
elements are Calrods (General Electric Co.) which are electrically heated
for transferring heat to air flowing across them. A thermostatic sensor
430 (FIG. 31) is located in the plenum and is connected to suitable
electrical circuitry for controlling the temperature of the heating
elements 428.
In the gas heated embodiment of the oven, a conventional configuration
implemented in known conveyorized impingement ovens is suitable (see e.g.,
U.S. Pat. No. 4,462,383, previously incorporated by reference). FIG. 31
shows both electrical and gas heating means options (both are not used
together). As shown in FIG. 31, the gas burner 450 is mounted in housing
452 and supplies the flame to heat the return air chamber. Other elements,
such as gas piping, a flame shaper and associated orifices, are not shown
since they are well known and conventionally associated with gas burners.
To regulate the temperature of the gas heat source, conventional control
means may be used. Preferably, a burner control is connected to an
electric valve which in turn is connected to a gas inlet pipe and
modulating control, all well known in the art. The modulating control
should be capable of regulating gas flow to the burner head by inputs
received from a thermostat sensor 430 (FIG. 31) located in the plenum.
Thermostat sensor 430 is able to sense the temperature of the air in the
plenum and to provide input to the modulating control. Upon receiving
inputs from the thermostatic sensor, the modulating control adjusts the
amount of gas supplied to the burner to maintain the selected oven
temperature.
Referring to FIGS. 4, 6, 8, and 32-33 in particular, the exhaust assembly
of the ovens shall now be described. Operably connected to plenum 320 is
exhaust assembly 500. Exhaust assembly 500 includes a first exhaust
conduit 502 attached to and in fluid communication with plenum 320 through
opening 504 in the plenum. A portion of the heated air is exhausted
through the exhaust conduit 502 during cooking as well as cleaning cycles.
From conduit 502 the heated exhaust gasses travel to and through vent pipe
assembly 506, which is in fluid communication with conduit 502. Exhaust
gasses are then released into the atmosphere through vertical vent pipe
assembly 506. Optionally, as shown in FIG. 33, vent pipe assembly 506 may
include a cyclonic separator assembly 508. Cyclonic separator assembly
includes a vertical (circular) conduit portion 510, a cone section 512,
and a plug 514. Exhaust gasses from exhaust conduit 502 enter vertical
conduit portion 510 adjacent the inner wall 516 so as to create a cyclonic
air flow pattern. This air flow pattern allows heated gasses to escape
upwardly through vent pipe 518 while solid particles entrained in the air
fall to the cone section 512. Plug 514 is periodically removed to clean
out deposits at the bottom of the cone section.
Optionally, the exhaust assembly 500 may also include a catalytic convertor
520 to remove entrained particles from the exhaust gas stream. FIGS.
11-12, 18, and 32-33 show a catalytic convertor 520 disposed in the
conduit 502 between plenum 320 and vent pipe assembly 506. The catalytic
convertor can be of the same type described heretofore. As shown in these
figures, catalytic convertor 520 is disposed within frame 522. Frame 522
is preferably constructed of materials capable of withstanding high
temperatures, most preferably above 900.degree. F. to accommodate the high
temperatures encountered during self-cleaning cycles. Suitable materials
include stainless steel and carbon steel.
In a preferred embodiment of the invention shown in FIGS. 30 and 32-33, the
oven is configured so that the cooling air being circulated through outer
cavity 60 and intermediate cavity 62 (the "cooling air stream") is mixed
and vented with high temperature gases exhausted from the plenum. This
configuration is particularly suitable for gas-heated ovens which are
required by regulations to exhaust a certain portion of the heated cooking
gas stream. By mixing the lower temperature cooling air stream with the
exhaust gas stream, the exhaust gas stream temperature is lowered
significantly. For example, an exhaust gas stream temperature of
900.degree. F. (cleaning cycle temperature) can be lowered well below
regulatory requirements by venting the cooling air stream into the plenum
exhaust stream. The above-described configuration is also preferred for
electric heated ovens to lower the high temperature exhaust gasses
produced by the oven during pyrolytic cleaning operations.
FIGS. 30 and 32-33 show this preferred configuration wherein the cooling
stream is mixed with the plenum exhaust stream. As shown, cooling air from
intermediate chamber 62, represented by the arrows, circulates through the
intermediate chamber 62 and is vented through opening 550 and into vent
pipe assembly 506 where it mixes with the exhaust gas stream. Similarly,
cooling air from outer cavity 60, represented by the arrows, circulates
through the outer cavity 60 and is vented through opening 552 and into
vent pipe assembly 506 where it also mixes with the exhaust gas stream.
Having described the various components of the oven above, a discussion of
the cooking air flow in the oven will be described below. Referring to
FIG. 30, air is heated in return air chamber 28b and is drawn into housing
302 by blower 330. The heated air then travels from blower 330 into plenum
320. Heated air exits plenum 320 through outlet openings 322 and enters
ducts 100 and 102 disposed above and below the conveyor. The heated air
then exits ducts 100 and 102 through openings 112 and impinges upon food
product traveling on the conveyor belt. Air in the cooking chamber next
travels through filter assemblies 130, 132. The cycled air is then exposed
to catalytic converters 162 disposed in the return air chamber of the
oven. The air is heated in the return air chamber 28b as the circulation
cycle repeats continuously. While most of the heated cooking air is
recycled and recirculated, a small portion of the heated air is vented
from the plenum 320 through the exhaust assembly 550 heretofore discussed
and described.
In the preferred embodiment shown in the drawings, the invention includes
self-cleaning capabilities using pyrolytic cleaning means. Assuming that
the oven has been operating at standard temperatures between 375.degree.
F.-425.degree. F. for a 10-hour day, the oven is likely to be at least
moderately soiled. During pyrolytic cleaning operations the conveyor is
operating so that the soiled conveyor belt and the cooking cavity of the
oven are cleaned. A conveyor speed of 6-10 minutes (i.e., pass through
time from entry to exit) is adequate. The steps of a preferred cleaning
operation are as follows:
To begin cleaning operations, the temperature of the oven is brought to
300.degree. F. When the oven has reached 300.degree. F., eyelids 27 (FIG.
31) are moved over the exit and entrance openings in the oven and the
diverter 408 is adjusted so that maximum air is diverted to the outer
cavity 60 [Position C] (see FIG. 30). With the diverter in this position,
cooling air is cut off to the intermediate cavity 62 thereby minimizing
the cooling of interior walls of the cooking chamber and allowing the
interior walls of the oven reach higher temperatures. Next, water
containing a small amount of detergent is sprayed into the cooking cavity.
Preferably, this is accomplished by spraying the water into the blower
wheel 330. FIG. 28 shows a structure that can be used for this purpose.
Referring to FIG. 28, pipe 600 is attached to reservoir 602 at opening
604. In use, the assembly is mounted to the exterior rear wall of the oven
adjacent the blower wheel, with the end 606 of the pipe 600 disposed
through the walls of the oven. Water is simply poured in the reservoir 602
and flows into the interior of the oven adjacent the blower wheel. When
the water/detergent mixture contacts the metal structures in the oven,
including the jet fingers, conveyor belt, and interior cooking cavity
walls, steam is created which softens and dissolves the grease and other
food deposits on the walls and other metal structures in the oven. The
softened and dissolved greases and deposits then run to the inclined floor
of the oven, into the drain 42 and out of the oven through pipe 43. This
step may be repeated if necessary.
A moderately to highly soiled oven will typically require 2-3 cycles of
water/detergent mixture. After the water/detergent cycle, a rinse cycle is
initiated by spraying water into the cooking cavity of the oven. It has
been found that two water rinse cycles are preferable. The water will cool
the oven interior substantially. When the temperature again reaches
300.degree. F., after the water rinse cycle or cycles, the rinse cycle is
complete.
Next, the temperature of the oven is brought up to 600.degree. F. and
remains at that temperature for approximately one hour or until the oven
stops producing smoke. Then the temperature is increased to 700.degree. F.
for approximately one hour, or again, until the oven stops producing
smoke. After the above step, the temperature in the interior of the oven
is increased to 900.degree. F. and remains at that temperature for
approximately one hour. Next, the temperature in the oven is reduced to
300.degree. F. and the diverter 408 is adjusted so that cooling air is
circulated into both the intermediate and outer cavities thereby
permitting the interior walls of the cooking cavity to cool. When the
temperature in the interior of the oven reaches 300.degree. F., two water
rinse cycles, as described above, are performed.
When the pyrolytic cleaning operations are completed, some amounts of white
ashy material may remain on the conveyor belt. These ashy deposits can be
simply removed by wiping the conveyor belt with a wet rag as the belt
moves. As stated above, a satisfactory belt speed for the cleaning
operation would be a rate of 6-10 minutes for a point on the belt to pass
through the cooking cavity.
After the final rinse cycles in the self-cleaning operation, the oven can
be brought up to standard cook temperature, e.g. 425.degree. F., to
prepare the oven for cooking. Preferably, the conveyor belt is conditioned
for the next cooking operation by simply wiping down the moving conveyor
with an oily rag while the oven is at cook temperature. This seasons the
belt and keeps product from sticking to the conveyor belt.
Preferably, cooking temperatures, cooking times, and the cleaning operation
of the oven are controlled with an electronic programmable controller.
Programmable controllers suitable for these purposes are well known in the
industry. For example, U.S. Pat. No. 4,462,383 (hereby incorporated by
reference) describes a suitable controller for ovens of the type described
herein. Referring to FIGS. 31 and 34, the controller components can be
housed in control center housing 700 which is secured to the oven cabinet
by welding, riveting or other suitable means. Cook time is dependent upon
the conveyor belt travel time through the oven. Temperatures and times can
be increased or decreased with up and down touch pad controls as shown in
FIG. 34. A digital display 702 indicates oven temperature and counts down
time remaining for the cycle being run.
To cook food in the above-described oven, the oven temperature and cook
time are selected for the particular food product. Suitable cooking
temperature typically range from 350-450.degree. F. A cook temperature
found to be suitable for many food products is 425.degree. F. After the
oven reaches the desired cook temperature, food product may be placed
directly on the moving conveyor belt and passes through the cooking
chamber. Table 1 shows cook temperatures and cook times for various food
products and compares the performance of the above-described oven
(designated Air Fry.TM.) with conventional ovens and fryers.
TABLE 1
______________________________________
Deep
Air Fry .TM. Fat Fry
425.degree. F.
Normal Cook 350.degree. F.
______________________________________
AIR FRY .TM. OVEN - Traditional Fried Products
Mrs Friday's Fish
6:00 20:00 - 375.degree. F.
6:00
McCarty's Chicken Tenders
5:30 14:00 - 400.degree. F.
5:30
Anchor Poppers .TM.
4:30 11:00 - 450.degree. F.
4:00
Ore Ida Mushrooms
4:30 7:00 - 475.degree. F.
3:00
Ore Ida Hash Browns
4:00 15:00 - 350.degree. F.
3:30
Ore Ida Premier Fries
3:30 2:30
Lamb Weston Stealth Fries
3:30 3:00
Ore Ida Spicy Fries
3:30 11:00 - 450.degree. F.
3:00
Ore Ida Zucchini Slices
3:30 7:00 - 450.degree. F.
3:00
Ore Ida Onion Rings
2:30 5:30 - 425.degree. F.
2:30
AIR FRY .TM. OVEN - Items not traditionally fried in deep fat fryer
Shrimp 2:00 4:00 - Grill
Hot dog 3:30 5:00 - Grill
Scallops 3:15 6:00 - Saute
Steak 3:30 (belt)
10:00 - Grill
Chicken breast 5:30 10:00 - Grill
Gourmet burger 6:45 7:00 - Grill
500.degree. F.
Burgers 4:20 (belt)
5:00 - Grill
Sausage Patties
4:20 (belt)
5:00 - Grill
LINCOLN IMPINGER .RTM. II
500.degree. F.
Burgers 6:30 (belt)
Sausage patties
6:30 (belt)
______________________________________
As demonstrated by Table 1, the oven described herein significantly reduces
cook times for various food products. At the same time, the oven also
allows traditionally deep fat fried foods to be cooked with air rather
than oil, thus providing a significant health benefit. Using air rather
than oil also eliminates the various inherent dangers of hot oil used in
deep fat frying. The present oven also represents a significant
improvement over known conveyorized impingement ovens. Specifically, the
present oven is capable of delivering heat transfer rates sufficiently
high to suitably cook foods which are traditionally deep fat fried.
Furthermore, conventional conveyorized ovens do not adequately address the
problem of grease capture and smoke elimination. Thus, food cooked in
conventional conveyorized ovens are typically placed in cooking pans or
other containment means.
It should be noted that the terms "upper" and "lower," "front" and "rear,"
"top" and "bottom," and "above" and "below" have been used to facilitate
the description of the illustrated embodiments of the invention and that
these terms are not intended to limit the scope of the invention. Further,
the terms "opening," "opening," "orifice," and "orifices" are intended to
include circular and non-circular openings, apertures or holes configured
to form and produce a stream of fluid. "Heating" is intended to mean the
transfer of heat to or from a product and includes cooling and "heated
air" is intended to mean heated gasses and heated air.
Although the present invention has been described with respect to preferred
embodiments, various changes, substitutions and modifications of this
invention may be suggested to one skilled in the art, and it is intended
that the present invention encompass such changes, substitutions and
modifications as fall within the scope of the appended claims.
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